Plasma processing apparatus

ABSTRACT

An apparatus includes a plasma processing container; a workpiece placement table disposed in the plasma processing container; a dielectric member having a facing surface that faces the workpiece placement table; an antenna provided on a surface of the dielectric member opposite to the facing surface and configured to introduce an induced electric field for plasma excitation into the plasma processing container via the dielectric member; an electromagnet group disposed along an outer circumference of the plasma processing container and configured to form a magnetic field in the plasma processing container; and a controller configured to control magnitudes of electric currents flowing through respective electromagnets of the electromagnet group differently from each other, to generate a magnetic gradient along a circumferential direction in the magnetic field that exists only in an outer circumferential space in the plasma processing container.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/840,636, filed on Dec. 13, 2017, which claims priority from JapanesePatent Application No. 2016-243451, filed on Dec. 15, 2016, all of whichare incorporated herein in their entireties by reference.

TECHNICAL FIELD

Various aspects and exemplary embodiments of the present disclosurerelate to a plasma processing apparatus.

BACKGROUND

There is a plasma processing apparatus using excitation of plasma by aninduced electric field. Such a plasma processing apparatus is called aninductively coupled plasma processing apparatus. The inductively coupledplasma processing apparatus includes, for example, a processingcontainer, a placing table, a dielectric member, and an antenna. Theplacing table is provided in the processing container and configured toplace a workpiece thereon. The dielectric member is provided above theplacing table. The antenna is a planar antenna provided on thedielectric member and introduces an induced electric field for plasmaexcitation into the processing container via the dielectric member.

In the inductively coupled plasma processing apparatus, a gas in theprocessing container is dissociated by the induced electric fieldintroduced into the processing container from the antenna, so thatplasma is generated. The plasma contains active species such as, forexample, ions and radicals. The ions and radicals contained in theplasma reach the workpiece placed on the placing table and react withthe surface of the workpiece, thereby performing a plasma processingsuch as, for example, etching or film formation. See, for example,Japanese Patent Laid-Open Publication No. 2010-153274.

SUMMARY

According to an aspect, the present disclosure provides a plasmaprocessing apparatus including a processing container; a placing tableprovided in the processing container and configured to place a workpiecethereon; a dielectric member having a facing surface that faces theplacing table; a planar antenna provided on a surface of the dielectricmember opposite to the facing surface and configured to introduce aninduced electric field for plasma excitation into the processingcontainer via the dielectric member; and an electromagnet group disposedalong an outer circumference of the processing container and configuredto form a magnetic field for moving ions in plasma based on the inducedelectric field along the facing surface of the dielectric member in theprocessing container.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a schematic configuration of aplasma processing apparatus according to an exemplary embodiment of thepresent disclosure.

FIG. 2 is a plan view illustrating an exemplary configuration of thehigh frequency antenna illustrated in FIG. 1.

FIG. 3 is a horizontal sectional view schematically illustrating anexemplary electromagnet group arranged along the outer circumference ofthe processing container of the plasma processing apparatus according tothe exemplary embodiment.

FIG. 4 is a view for explaining an action of a horizontal magnetic fieldformed by the electromagnet group.

FIG. 5 is a horizontal sectional view schematically illustrating anotherexemplary electromagnet group arranged along the outer circumference ofthe processing container of the plasma processing apparatus according tothe exemplary embodiment.

FIG. 6 is a view for explaining an action of a cusp magnetic fieldformed by the electromagnet group.

FIG. 7 is a view for explaining a gradient of the magnetic fieldstrength.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawing, which form a part hereof. The illustrativeembodiments described in the detailed description, drawing, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made without departing from the spirit or scope ofthe subject matter presented here.

In the related art, it is not taken into account to appropriatelycontrol the ratio of the ions and radicals reaching the workpiece.

According to an aspect, the present disclosure provides a plasmaprocessing apparatus including a processing container; a placing tableprovided in the processing container and configured to place a workpiecethereon; a dielectric member having a facing surface that faces theplacing table; a planar antenna provided on a surface of the dielectricmember opposite to the facing surface and configured to introduce aninduced electric field for plasma excitation into the processingcontainer via the dielectric member; and an electromagnet group disposedalong an outer circumference of the processing container and configuredto form a magnetic field for moving ions in plasma based on the inducedelectric field along the facing surface of the dielectric member in theprocessing container.

In the above-described plasma processing apparatus, the electromagnetgroup forms a magnetic field that traverses a central space in theprocessing container and an outer circumferential space surrounding thecentral space as the magnetic field.

In the above-described plasma processing apparatus, the electromagnetgroup forms a magnetic field that exists only in the outercircumferential space in the processing container among the centralspace in the processing container and the outer circumferential spacesurrounding the central space, as the magnetic field.

The above-described plasma processing apparatus further includes acontroller that controls magnetic poles of respective electromagnets ofthe electromagnet group to switch the magnetic field formed by theelectromagnet group to a first magnetic field that traverses the centralspace in the processing container and the outer circumferential spacesurrounding the central space, or a second magnetic field that existsonly in the outer circumferential space in the processing container.

In the above-described plasma processing apparatus, the controllerswitches the magnetic field formed by the electromagnet group to thefirst magnetic field or the second magnetic field according to aswitching timing of a plasma processing process executed by the plasmaprocessing apparatus.

In the above-described plasma processing apparatus, the controllercontrols a magnitude of a current flowing through the electromagnets ofthe electromagnet group to generate a gradient in a magnetic fieldstrength of the magnetic field formed by the electromagnet group.

The above-described plasma processing apparatus further includes asupport member configured to rotatably support the electromagnet groupabout a central axis of the processing container. The controllercontrols the support member to rotate the magnetic field formed by theelectromagnet group about the central axis of the processing container.

According to the aspect of the above-described plasma processingapparatus, it is possible to appropriately control the ratio of the ionsand radicals reaching the workpiece.

Hereinafter, exemplary embodiments of the plasma processing apparatusdisclosed herein will be described in detail with reference to drawings.Meanwhile, in the respective drawings, the same or corresponding partswill be denoted by the same symbols.

(Exemplary Configuration of Plasma Processing Apparatus)

First, an exemplary configuration of a plasma processing apparatus 100according to an exemplary embodiment of the present disclosure will bedescribed with reference to the drawings. Here, an inductively coupledplasma processing apparatus will be exemplified, which performs apredetermined plasma processing on a semiconductor wafer (hereinafter,simply referred to as a “wafer”) serving as a workpiece with plasma of aprocessing gas excited in the processing container by applying a highfrequency power to a planar high frequency antenna. FIG. 1 is asectional view illustrating a schematic configuration of a plasmaprocessing apparatus 100 according to the exemplary embodiment. FIG. 2is a plan view illustrating an exemplary configuration of a highfrequency antenna 140 illustrated in FIG. 1.

As illustrated in FIG. 1, the plasma processing apparatus 100 includes aprocessing container (chamber) 102 formed of metal (e.g., aluminum) in atubular (e.g., cylindrical) shape. The shape of the processing container102 is not limited to the cylindrical shape. For example, the shape ofthe processing container 102 may be a prismatic shape (e.g., a boxshape).

A placing table 110 is provided on the bottom surface of the processingcontainer 102 to place the wafer W thereon. The placing table 110 isformed of, for example, aluminum in a substantially pillar shape (e.g.,columnar shape). The shape of the placing table 110 is not limited tothe columnar shape. For example, the shape of the processing container102 may be a prismatic shape (e.g., polygonal prism). Although notillustrated, various functions (e.g., an electrostatic chuck thatattracts and holds the wafer W by Coulomb force and a temperatureadjustment mechanism such as, for example, a heater or a coolant flowpath) may be provided on the placing table 110 as required.

On the ceiling portion of the processing container 102, a plate-likedielectric member 104 made of, for example, quartz glass or ceramic isprovided to face the placing table 110. Specifically, the dielectricmember 104 is formed, for example, in a disc shape and hermeticallyattached to close the opening formed in the ceiling portion of theprocessing container 102. The dielectric member 104 has a facing surface104 a that faces the processing table 110.

The processing container 102 is provided with a gas supply unit 120 thatsupplies, for example, a processing gas for processing the wafer Wthereto. The gas supply unit 120 is configured, for example, asillustrated in FIG. 1. That is, a gas introduction port 121 is formed inthe side wall portion of the processing container 102, and a gas source122 is connected to the gas introduction port 121 via a gas supply pipe123. A flow rate controller for controlling the flow rate of theprocessing gas, for example, a mass flow controller (MFC) 124 and anopening/closing valve 126 are disposed at portions of the gas supplypipe 123. With the gas supply unit 120, the processing gas from the gassupply source 122 is controlled at a predetermined flow rate by the MFC124 and is supplied from the gas introduction port 121 into theprocessing container 102.

In FIG. 1, to simplify the description, the gas supply unit 120 isrepresented by a single gas line system. However, the gas supply unit120 is not limited to the case of supplying the processing gas of asingle gas type, and may supply a plurality of gas species as processinggases. In this case, a plurality of gas supply sources may be providedto constitute a multiple gas line system, and a mass flow controller maybe provided in each gas line. In FIG. 1, the case where the gas supplyunit 120 is configured to supply a gas from the side wall portion of theprocessing container 102 is exemplified, but the present disclosure isnot limited thereto. For example, the gas may be supplied from theceiling portion of the processing container 102. In this case, forexample, a gas introduction port may be formed in, for example, thecenter of the dielectric member 104, and the gas may be suppliedtherefrom.

As a processing gas to be supplied into the processing container 102 bythe gas supply unit 120, for example, a halogen-based gas containing,for example, Cl is used for etching of an oxide film. Specifically, whenetching a silicon oxide film (e.g., a SiO₂ film), for example, CHF₃ gasis used as a processing gas. Further, when a high dielectric thin film(e.g., HfO₂, HfSiO₂, ZrO₂, or ZrSiO₄) is etched, BCl₃ gas is used as aprocessing gas, or a mixed gas of BCl₃ gas and O₂ gas is used as aprocessing gas.

An exhaust unit 130 is connected to the bottom surface of the processingcontainer 102 via an exhaust pipe 132 to exhaust the atmosphere insidethe processing container 102. The exhaust unit 130 is constituted by,for example, a vacuum pump, and is configured to reduce the pressure inthe processing container 102 to a predetermined pressure. A wafercarry-in/out port 134 is formed in the side wall portion of theprocessing container 102, and a gate valve 136 is provided in the wafercarry-in/out port 134. For example, at the time of the carry-in of thewafer W, the gate valve 136 is opened, so that the wafer W is placed onthe placing table 110 in the processing container 102 by a conveyancemechanism such as, for example, a conveyance arm (not illustrated).Then, the gate valve 136 is closed, and a processing is performed on thewafer W.

A planar high frequency antenna 140 is disposed on a surface 104 b ofthe dielectric member 104 opposite to the facing surface 104 a. The highfrequency antenna 140 introduces an induced electric field for plasmaexcitation into the processing container 102 via the dielectric member104. The high frequency antenna 140 is formed by holding a spiralantenna element 142 made of a conductor (e.g., copper, aluminum, orstainless steel) with a plurality of holding members 144. For example,as illustrated in FIG. 2, three holding members 144 each formed in a rodshape are disposed radially from the vicinity of the center of theantenna element 142 to the outside thereof.

The antenna element 142 is connected with a high frequency power source150. The high frequency power source 150 supplies a high frequency powerof a predetermined frequency (e.g., 27.12 MHz) to the antenna element142. Then, an induced electric field for plasma excitation is introducedinto the processing container 102 via the dielectric member 104 by theantenna element 142 supplied with the high frequency power. Then, thegas introduced into the processing container 102 is excited by theinduced electric field introduced into the processing container 102 togenerate plasma, and a predetermined plasma processing (e.g., an ashingprocessing, an etching processing, or a film forming processing) isperformed on the wafer W. The high frequency power output from the highfrequency power source 150 is not limited to 27.12 MHz. The highfrequency power may be, for example, 13.56 MHz or 60 MHz. However, it isnecessary to adjust the electrical length of the antenna element 142depending on the high frequency power output from the high frequencypower source 150.

The height of the high frequency antenna 140 may be adjusted by anactuator 148.

A substantially tubular (e.g., cylindrical) shield member 160 isprovided on the ceiling portion of the processing container 102 to coverthe high frequency antenna 140. The shape of the shield member 160 isnot limited to the cylindrical shape. The shield member 160 may have anyshape such as, for example, a prismatic shape, but the shape thereof maymatch the shape of the processing container 102. Here, for example,since the processing container 102 is formed in a substantiallycylindrical shape, the shield member 160 is correspondingly formed in asubstantially cylindrical shape. Further, when the processing container102 has a substantially prismatic shape, the shield member 160 may alsohave a substantially prismatic shape. Further, the height of the highfrequency antenna 160 may be adjusted by an actuator 168.

Further, on the outer circumference of the processing container 102, anelectromagnet group 171 is disposed along the outer circumference of theprocessing container 102. The electromagnet group 171 forms a magneticfield in the processing container 102 to move ions in the plasma basedon the induced electric field introduced into the processing container102 from the high frequency antenna 140 along the facing surface 104 aof the dielectric member 104. The electromagnet group 171 sets magneticpoles of the electromagnet group 171 under the control of a controller200 (to be described later).

FIG. 3 is a horizontal sectional view schematically illustrating anexample of the electromagnet group 171 arranged along the outercircumference of the processing container 102 of the plasma processingapparatus 101 according to the exemplary embodiment. As illustrated inFIG. 3, the electromagnet group 171 is configured by arranging aplurality of electromagnets 172 in a ring shape. In the example of FIG.3, sixteen electromagnets 172 are arranged in a ring shape. In theelectromagnet group 171, when receiving a “first switching controlsignal” from the controller 200, the magnetic poles of the respectiveelectromagnets 172 are set such that the direction of the magnetic polesof the electromagnets 172 arranged in one section among two sectionssectioned in the circumferential direction of the electromagnet group171 and the direction of the magnetic poles of the electromagnets 172arranged in the other section are opposite to each other. In the exampleof FIG. 3, the section on the left side and the section on the rightside in the circumferential direction of the electromagnet group 171 aresectioned, and the direction of the magnetic poles of the eightelectromagnets 172 arranged in the left section and the direction of themagnetic poles of the eight electromagnets 172 arranged in the rightsection are opposite to each other. The electromagnet group 171 forms amagnetic field that traverses the central space in the processingcontainer 102 and the outer circumferential space surrounding thecentral space, based on the magnetic poles of the respectiveelectromagnets 172 set as illustrated in FIG. 3. The magnetic field thattraverses the central space in the processing container 102 and theouter circumferential space surrounding the central space is also calleda “horizontal magnetic field.” Here, the central space in the processingcontainer 102 is, for example, a space corresponding to the region ofthe wafer W in the processing container 102. Further, the outercircumferential space in the processing container 102 is, for example, aspace corresponding to the region surrounding the wafer W in theprocessing container 102.

FIG. 4 is a view for explaining an action of a horizontal magnetic fieldformed by the electromagnet group 171. When a horizontal magnetic fieldM1 is generated in the processing container 102 by the electromagnetgroup 171 in a state where plasma based on the induced electric fieldfrom the high frequency antenna 140 is generated, electrons in theplasma are wound around magnetic force lines of the horizontal magneticfield M1 and reciprocate along the magnetic force lines. In addition,since the Larmor radius decreases as the magnetic flux densityincreases, the electron density at the position of the height of themagnet having a high magnetic flux density increases, and the electrondensity around the periphery (above and below the magnet center)decreases. Further, since cations in the plasma are attracted to theelectrons to maintain electric neutrality, the density in the heightdirection of the cations is the highest at the height of the magnetcenter as well. Thus, the amount of the cations reaching the wafer W issuppressed in both the central portion and the edge portion of the waferW. Meanwhile, radicals in the electrically neutral plasma descend towardthe wafer W without receiving a force from the horizontal magnetic fieldM1. As a result, the ratio of the ions and radicals reaching the wafer Wis appropriately controlled.

FIG. 5 is a horizontal sectional view schematically illustrating anotherexample of the electromagnet group 171 arranged along the outercircumference of the processing container 102 of the plasma processingapparatus 101 according to the exemplary embodiment. As illustrated inFIG. 5, the electromagnet group 171 is configured by arranging aplurality of electromagnets 172 in a ring shape. In the example of FIG.5, sixteen electromagnets 172 are arranged in a ring shape. In theelectromagnet group 171, when receiving a “second switching controlsignal” from the controller 200, the magnetic poles of the respectiveelectromagnets 172 are set such that the directions of the magneticpoles of the electromagnets 172 arranged in mutually adjacent sectionsamong a plurality of sections sectioned in the circumferential directionof the electromagnet group 171 are opposite to each other. In theexample of FIG. 5, sixteen sections are sectioned in the circumferentialdirection of the electromagnet group 171, and the directions of themagnetic poles of the electromagnets 172 arranged in mutually adjacentsections are opposite to each other. The electromagnet group 171 forms amagnetic field that exists only in the outer circumferential space inthe processing container 102 among the central space in the processingcontainer 102 and the outer circumferential space surrounding thecentral space, based on the magnetic poles of the respectiveelectromagnets 172 set as illustrated in FIG. 5. The magnetic field thatexists only in the outer circumferential space in the processingcontainer 102 is called a “cusp magnetic field.” Here, the central spacein the processing container 102 is, for example, a space correspondingto the region of the wafer W in the processing container 102. Further,the outer circumferential space in the processing container 102 is, forexample, a space corresponding to the region surrounding the wafer W inthe processing container 102.

FIG. 6 is a view for explaining an action of a cusp magnetic fieldformed by the electromagnet group 171. When a cusp magnetic field M2 isgenerated in the processing container 102 by the electromagnet group 171in a state where plasma based on the induced electric field from thehigh frequency antenna 140 is generated, electrons present in the outercircumferential space in the processing container 102 among theelectrons in the plasma are moved along the facing surface 104 a of thedielectric member 104 in the outer circumferential space in theprocessing container 102 by the force received from the cusp magneticfield M2. Then, cations present in the outer circumferential space inthe processing container 102 among the cations in the plasma areattracted to electrons and moved along the facing surface 104 a of thedielectric member 104 in the outer circumferential space in theprocessing container 102. Meanwhile, radicals in the electricallyneutral plasma and cations present in the central space in theprocessing container 102 among the cations in the plasma descend towardthe wafer W without receiving a force from the cusp magnetic field M2.Thus, the amount of the cations reaching the wafer W only at the edgeportion of the wafer W is suppressed, while the amount of the cationsreaching the wafer W at the central portion of the wafer W ismaintained. As a result, the ratio of the ions and radicals reaching thewafer W is appropriately controlled.

The description will refer back to FIG. 1. The plasma processingapparatus 100 is connected with the controller (overall control device)200, and each part of the plasma processing apparatus 100 is controlledby the controller 200. Further, the controller 200 is connected with anoperation unit including, for example, a keyboard through which anoperator performs an input operation of a command to manage the plasmaprocessing apparatus 100, and a display that visually displays theoperation state of the plasma processing apparatus 100.

Further, the controller 200 is connected with a storage unit 220 thatstores, for example, a program for implementing various processingsperformed by the plasma processing apparatus 100 under the control ofthe controller 200 or recipe data necessary for executing the program.

The storage unit 220 stores, for example, a recipe for performing anecessary processing (e.g., a cleaning processing) in the processcontainer 102, in addition to a plurality of process processing recipesfor performing a process processing of the wafer W. The recipes arethose obtained by summarizing a plurality of parameter values such as,for example, control parameters for controlling respective parts of theplasma processing apparatus 100 and setting parameters. For example, theprocess processing recipes have parameter values such as, for example, aprocessing gas flow rate ratio, a processing container internalpressure, and a high frequency power.

The recipes may be stored in a hard disk or a semiconductor memory, ormay be set in a predetermined position of the storage unit 220 whilebeing stored in a storage medium readable by a portable computer suchas, for example, a CD-ROM or a DVD.

The controller 200 reads a desired process processing recipe from thestorage unit 220 based on, for example, an instruction from theoperation unit 210 and controls each part to execute a desiredprocessing in the plasma processing apparatus 100. Further, the recipesmay be edited by an operation from the operation unit 210.

The controller 200 switches the magnetic field formed by theelectromagnet group 171 to a horizontal magnetic field or a cuspmagnetic field by controlling the magnetic poles of the electromagnets172 of the electromagnet group 171. Specifically, the controller 200switches the magnetic field formed by the electromagnet group 171 to ahorizontal magnetic field or a cusp magnetic field according to theswitching timing of the plasma processing performed by the plasmaprocessing apparatus 100. Hereinafter, details of the switching controlof the magnetic field by the controller 200 will be described.

For example, it is assumed that the plasma processing apparatus 100continuously executes a first plasma processing process, a second plasmaprocessing process, and a third plasma processing process. In the firstplasma processing process and the third plasma processing process, it isassumed that a desired plasma processing may be performed by keeping theratio of ions to radicals reaching the wafer W relatively low.Meanwhile, in the second plasma processing process, it is assumed that adesired plasma processing may be performed by keeping the ratio of ionsto radicals reaching the wafer W relatively high.

In this case, the controller 200 controls the magnetic poles of therespective electromagnets 172 of the electromagnet group 171 using the“first switching control signal” during the period in which the firstplasma processing process is executed, so that the magnetic field formedby the electromagnet group 171 is switched to the horizontal magneticfield. Thus, during the period in which the first plasma processingprocess is executed, the amount of the cations reaching the wafer W issuppressed in both the central portion and the edge portion of the waferW. As a result, the ratio of ions to radicals reaching the wafer W iskept relatively low.

Meanwhile, the controller 200 controls the magnetic poles of therespective electromagnets 172 of the electromagnet group 171 using the“second switching control signal” at the timing when the first plasmaprocessing process is switched to the second plasma processing process,so that the magnetic field formed by the electromagnet group 171 isswitched to the cusp magnetic field. Thus, during the period in whichthe second plasma processing process is executed, the amount of thecations reaching the wafer W only at the edge portion of the wafer W issuppressed, while the amount of the cations reaching the wafer W at thecentral portion of the wafer W is maintained. As a result, the ratio ofions to radicals reaching the wafer W is kept relatively high.

Then, the controller 200 controls the magnetic poles of the respectiveelectromagnets 172 of the electromagnet group 171 using the “firstswitching control signal” at the timing when the second plasmaprocessing process is switched to the third plasma processing process,so that the magnetic field formed by the electromagnet group 171 isswitched back to the horizontal magnetic field. Thus, during the periodin which the third plasma processing process is executed, the amount ofthe cations reaching the wafer W is suppressed in both the centralportion and the edge portion of the wafer W. As a result, the ratio ofions to radicals reaching the wafer W is kept relatively low.

Further, the controller 200 may generate a gradient in the magneticfield strength of the magnetic field formed by the electromagnet group171 by controlling the magnitude of the current flowing through eachelectromagnet 172 of the electromagnet group 171.

FIG. 7 is a view for explaining the gradient of the magnetic fieldstrength. In FIG. 7, it is assumed that the magnetic field formed in theprocessing container 102 by the electromagnet group 171 is a cuspmagnetic field. Since the antenna element 142 of the high frequencyantenna 140 is arranged in a spiral shape, the processing container 102has a space A1 having a relatively large number of spiral portions ofthe corresponding antenna element 142 and a space A2 having a relativelysmall number of spiral portions of the corresponding antenna element142. The number of spiral portions of the antenna element 142corresponding to the space A1 is three, and the number of spiralportions of the antenna element 142 corresponding to the space A2 istwo. The electric field strength of the induced electric fieldintroduced into the processing container 102 from the high frequencyantenna 140 varies depending on the number of spiral portions of theantenna element 142. In the example of FIG. 7, since the number ofspiral portions of the antenna element 142 corresponding to the space A1is larger than the number of spiral portions of the antenna element 142corresponding to the space A2, the electric field strength of theinduced electric field introduced into the space A1 becomes larger thanthe electric field strength of the induced electric field introducedinto the space A2. Then, when the electric field strength of the inducedelectric field varies, the plasma density distribution of the plasmabased on the induced electric field introduced into the processingcontainer 102 from the high frequency antenna 140 becomes non-uniform inthe processing container 102. In the example of FIG. 7, since theelectric field strength of the induced electric field introduced intothe space A1 is larger than the electric field strength of the inducedelectric field introduced into the space A2, the plasma density in thespace A1 becomes larger than the plasma density in the space A2.

Therefore, in order to resolve the non-uniformity of the plasma densitydistribution, the controller 200 generates a gradient in the magneticfield strength of the magnetic field formed by the electromagnet group171 by controlling the magnitude of the current flowing through eachelectromagnet 172 of the electromagnet group 171. Specifically, thecontroller 200 generates a gradient in the magnetic field strength ofthe magnetic field formed by the electromagnet group 171 such that themagnetic field strength of the magnetic field formed in the space A2 islarger than the magnetic field strength of the magnetic field formed inthe space A1. Therefore, the electrons and cations drawn to the space A2are larger than the electrons and cations drawn to the space A1, and asa result, it is possible to make the plasma density distributionuniform.

As described above, according to the plasma processing apparatus 100 ofthe exemplary embodiment, since the electromagnet group 171 is disposedalong the outer circumference of the processing container 102, it ispossible to form a magnetic field in which the ions in the plasma basedon the induced electric field introduced from the planar high frequencyantenna 140 are moved along the facing surface 104 a of the dielectricmember 104. Thus, the amount of the cations reaching the wafer W issuppressed. As a result, the ratio of the ions and radicals reaching thewafer W may be appropriately controlled.

Further, according to the plasma processing apparatus 100 of theexemplary embodiment, the magnetic field formed by the electromagnetgroup 171 is switched to a horizontal magnetic field or a cusp magneticfield according to the switching timing of the plasma processingperformed by the plasma processing apparatus 100. Thus, when executing aplurality of plasma processing processes, it is possible to switch themagnetic field formed by the electromagnet group 171 to a magnetic fieldsuitable for each plasma processing process.

Further, according to the plasma processing apparatus 100 of theexemplary embodiment, a gradient is generated in the magnetic fieldstrength of the magnetic field formed by the electromagnet group 171 bycontrolling the magnitude of the current flowing through eachelectromagnet 172 of the electromagnet group 171. Thus, it is possibleto make the plasma density distribution uniform.

Further, the disclosed technique is not limited to the above-describedexemplary embodiment, and various modifications may be made within thescope of the disclosure.

For example, in the above-described exemplary embodiment, theelectromagnet group 171 is disposed along the outer circumference of theprocessing container 102, but the plasma processing apparatus 100 mayfurther include a support member that rotatably supports theelectromagnet group 171 around the central axis of the processingcontainer 102. In this case, the controller 200 may further control thesupport member to rotate the magnetic field formed by the electromagnetgroup 171 around the central axis of the processing container 102. Thus,it is possible to more efficiently make the plasma density distributionuniform.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. An apparatus comprising: a plasma processingcontainer; a workpiece placement table disposed in the plasma processingcontainer; a dielectric plate having a facing surface that faces theworkpiece placement table; an antenna provided on a surface of thedielectric plate opposite to the facing surface and configured tointroduce an induced electric field for plasma excitation into theplasma processing container via the dielectric plate, the antennaincluding a planar spiral antenna having spiral portions divided into afirst segment and a second segment; an electromagnet group including aplurality of electromagnets disposed along an outer circumference of theplasma processing container and configured to form a magnetic field inthe plasma processing container; and a controller configured to controlmagnitudes of electric currents flowing through respectiveelectromagnets of the electromagnet group differently from each other,to generate a magnetic gradient along a circumferential direction in themagnetic field that exists only in an outer circumferential space in theplasma processing container, wherein: a first space of the plasmaprocessing container corresponding to the first segment has a greaternumber of spiral portions of the planar spiral antenna than a secondspace of the plasma processing container corresponding to the secondsegment, the controller is configured to generate the magnetic gradientalong the circumferential direction in the magnetic field such that amagnetic field strength in the second space is larger than a magneticfield strength in the first space, and the first space is adjacent tothe second space in the circumferential direction.
 2. The apparatus ofclaim 1, wherein the controller is configured to control magnitudes ofelectric currents flowing through respective electromagnets of theelectromagnet group differently from each other, to switch the magneticfield that exists only in the outer circumferential space in the plasmaprocessing container, or a horizontal magnetic field that traverses acentral space in the plasma processing container and the outercircumferential space surrounding the central space.
 3. The apparatus ofclaim 2, wherein the planar spiral antenna is made of a conductor heldby a plurality of holders on the surface of the dielectric plateopposite to the facing surface.
 4. The apparatus of claim 1, furthercomprising: a support configured to rotatably support the electromagnetgroup about a central axis of the plasma processing container, whereinthe controller controls the support to rotate the magnetic field formedby the electromagnet group about the central axis of the plasmaprocessing container.
 5. The apparatus of claim 4, wherein the planarspiral antenna is made of a conductor held by a plurality of holdingmembers on the surface of the dielectric plate opposite to the facingsurface.
 6. The apparatus of claim 1, wherein the number ofelectromagnets disposed adjacent to the second space is greater than thenumber of electromagnets disposed adjacent to the first space.
 7. Theapparatus of claim 1, wherein the second space is greater than the firstspace.